Multiplex telegraph system.



i. P. D. HUGE.

Patented June 25, 1912.

2 SHEBTST SHEET 1.

W H m/coma J. F. D. HUGE.

MULTIPLEX TELEGRAPH SYSTEM.

APPLICATION FILED JULY 27,1910v msmsa Patented June 25, 1912.

2 SHEETS-SHEET 2.

'JosEPHr. n1: HOGE,

or new yorimlnQxQQnssiGirofi 'zrdmnmcan ms'rnre'r TELE- GRAPH commune conrona'rronor New ,rnnsnr.

I i s aflgting gig otters Patentv Origtnal 'applicatienjfiled AnrililllQlO, Serial K0. $51,688:1Divided and thls ap plication illedlJ'uly 27,

Beit known that I, .J'osmi a citizen of the -United- States, residing-jat New Yorlninthe county of- New York and 5 State of NewYor'k, have invented a-certainv i Myfinvention: relates to iinprovementsiin multiplex telegraph-'- systems; and ipartieu? larly" call bog: signal ng system'sQ- s'uch as d1s.-.

trictmessenger systems,'watchmns-systems,

fire, alarmsystems, etc., and constitutes 'a A specific form of the system illustrated "and desei'ibed, in my. application; filed A T111151,

1910, sane; 554 668, o fiwhich'appication thepresent a plicationis a division. Ifyvill;

particularly escribe herein myrinvention, as applied, to,.distri'et m'esscn .er systems jmd I like signaling systems,;invo v-ing-Ithe use of call' boxes.(it being understdodtliiitfire alarm boxes and other like automatic teIegraphtransmitters are, in'a general sense,"

the equivalent, in aeiystem such asl"here 1n described; of district messengercallboxs) it being iunderstood that in illustrating {theembodiment of my inve'ntionin such a ,sys--.

tem I do not limit it 'to use in suclifsystems',

but? that it is applicable tojgeneraltelegraphy as indicated in saidqapplication S r;

N0."55- 1,6G8, a v I In 'district messenger systems fire alarm systems, and the .like, it is customary" to provide a number of call boxes in a single on:-

Ieuit, these boxes adapted each to transmit a signal (usuall a number) different fro a central station. In practice-there are good service; this number varying more For less accordmgto local cond tions, butslncea number of suchcireuits leading to the same central station, and the'calliboxes or transmittin devices of'each gircuitare usually soniew at close together. lhere is a practical limit to the number of.boxes that may be placed llll any one circuit, and give in general any such system will comprisecircuit conductors of considerable length leading from the central station to the vicinity where the boxes are located, a; considerable economy. may be effected if these same a conductors may be. used for transmitting the "signalsof: an entirely :distinct group {of the mitting and rece ving devices, are. already r quenc y, the inductance coil being firmcipall tefiective "to exclude currents of 1910. Serial ltd- $4,204.

boxes prov-ided. no interference between the signals of the. different groups ofboxesre- .sultsQ This accornnlish accordingto mypresent invention. arrange to impose 'upon the same circuit conductors two dis '60 a tinetcurrents, one a direct current, the other analternatmg current of somewhat-high s quence-fi pr v W g p f w i call eboires, onearranged afiectrthevdirect' ji' current," thej other tQafi'ectTthe alternating current; and I v"provide two' distinct receivefl ing 'devices, onelfor thedirectcu-rrent signals, the othrifor tlie 1lternating c11rr'ent'-.

sign'aljsr Bet veen thejdirect currentboxes and thelinejcondnctors, and between the direct current receiving devices and the line conductors I provide means for preventing "theseiins'truments gtrombeingafiected-byor v 1 froln a'fi'eting,=thel alternating currents ;and

- between the alternating cnrrentboxes and 2i .theliiie conductors and-the alternating cur rent receiving "devices-and the. line conductors, I interpose-ineansfor preventing such dev'ces from. being affected by, or affecting, 4

' irect currents ;The directcurrenttranswell known in the art. Y

'- The-isolationof theseVeraI-systems) em ploymg the same. line conductors, according to mymvention, depends (first) on the fact that aninductance (N l, jean be constructed which for any given conditions will limit the passage of an alternatng current through it w to anyde'sired value,'however.small,. (thou h the signals of t me other boxes in'the same;

, circuit, suitable receiving. devices being 10- cated atwhat for convenience may be-termed;

very small impedance to an alternating curs? rent of .a givenifrequency, but will offer .9; a i great impedance to oneof'a higher or lower requenc the condenser l'bemg *efi'ejctivej principa y to exclude currents of I Weffre-E igherffre quency, so that it is possible to limit the pas difierent frequency to any given value, how- I and operating normally through a metallic ever small, even though 1n practice it be impossible to exclude such second alternating current altogether, though possible to reduceit to such value that it does not produce material disturbance.

In essential rinciple, the exclusion of a direct current m the alternating current system or systems, is-somewhat'sunilar to excluding an alternating current of lower frequency from systems 1n which alternating currents of higher frequency are used for while a condenser will pass no current tor a constant direct potential after once charged,

a pulsating direct current will,-.give rise to' an alternating: current; through the gondenser, the condenser accepting'.-current in one direction to charge-it as the otential rises, and passing it in the opposite 'rection by discharging as the potential falls.

currents in telegraph and like signaling systems, embodying ,rel'ays, difii'culty, has been experienced in l'obtaining good contacts at the contact-points'of, relays operated by alternating .currents f;llherc being, a, tendency for thearmatureEtojEave the contact point at-theinstant of currentjreversal, According to my resentinvention overcome this tendency, y the use, nixconnectlon with each such relay, of a current rectifien which transforms the electricicurrent .of the line mto a direct current, in so far as the 0011s or"- the relay are concerned. ivarlous es of these rectifiers are known,f,and I'do :1 "limit myself. to any particular-type though I have ier'ein one type of for the purpose i;

The objects of my inventionare to increase the service capacity" of 'telegraph,

alarm, and OthGIf SJQQlIDg circuits and the paratus like, without detriment to the service given, to avoidc'onflict between the several superimposed signaling systems, to make the apquiredsimple, easily understood, easily justed, and relatively inexpensive, to make" the complete, system operate correctlyeith'er over ametalliccircuit or over ground return circuits, andto' provide for the conversion at will of a metallic circuit system intotwo independentgroun'd return systems, and vice versa, andto make the systern as a whole '0 eratii'zewi'th currents of w th. instruments of a simp e and rclativelydnexpensive type.

low oten tial' an I will now proceed to describe my.'in've: 1- tion with reference to the accom anying drawin s, illustrating'm ore or'l'css iagram matical y different arrangements" of circuits and instruments embodying myi-nv'ention.

In saiddrau'iugs: Figure 1' shows dia-' grammatically a call box systcfuconiprising adircct current and an alternating current side, using the. same line conductors .cally in Fig. 1. Referring now to circuit but adapted at will to bechanged into two separatesystems comprising each a line conductor and a ground return; Fig. 2 Shows an elevation and partial section-of a 7 0 rectifier such as is illustrated diagrarm'natithe drawings, and at. first to Fig. 1, .1 and 2'designate line conductoraserving bath for the primary or direct currentsignaling circuit and for the alternating current circuit, before referred to. 3, 3 designate ordinary call boxes, 6. e.,

signal transmitters, in aprirnary circuit 4 connected to the line conductors 1 and 2 through inductive resistances 5; and 6 des-- ignates'a corresponding direct current re- .ceiving set, at a central station, connected to line conductors-1 and-2 through inductive resistance 7. The call boxes 3 are tobe Heretofore in attempts to use alternating.

understood to beef any well'known type and for ordinary call, signal, or alarm service are preferably arranged to work according' to the well-known McCulloh stern, each having, as is customary in suclf oxes, two signal wheels of similar signal numbers, one arranged to work through the metallic circuit, the otherto work through a ground return, each such box having a ground con- 'nection'8. The receiving set 6 is of the gen- I eral nature of such sets as commonly em-- ployed in district telegraph work, compris mg receivin relays 9: and 10, (in this 53 5-- tern usually caving resistance of from 600 to IOOOoh'Ins) areceivingiregister'll,and afurther receiving device 12, also a double-throw multiole switch 13, commonly termed a" McCu lohswitch-in a system such as this,

by which the circuit comprising conductors 1 and 2 may be converted, at will, into two separate ground-return circuits, according to the well-known McCulloh system.- -The general arrangement of the instrument of the receiving set 6, shown in the drawings,

is that ofthe patent to Hamblin No. 808,451, dated Dec; 26, 1905. 14 designates a. direct current i generator, 14 another direct-curs rent generator supplying current to the local circuit of receiving sets 6 and 20, and 15, 15 suitable non-inductive resistances of fr' in 1 15 250 to 300 ohms-imany case, a resistance high enough tormakemesistance, rather than inductance, the controlling factor in the localcircuits of the direct/current receivinga set 6.. @therwise, the inductance of theflocal direct-current receiving apparatus would delay the current rise and fall andso prevent it responding to impulses of short duration .in.thcdesired-manner. 16, '16 designates call boxes similar; tp12a 1 .boxes 3. but located in a circuit 17 connected :to conductors l and 2 respectively, through ccndcnsers18 and inductive resistances 19.

2015 a receiving set, for boxes 16,-arrungt'ri to be operated by'alternuting curconductors 1 and 2, '15

designates an altcrna'ting'current genorator for-supplying. current to receiving set 20 and boxes 16.

Receiving set.20 is in general the same as set 6, comprising relays 24 and 25, a register 26, another signal receiving device 27, and a double-throw multi-pole McCulloh.switch 28, by which the circuit 17, the alternating currentv of which is su direct current of circuit 4 flowing through k may be converted, at will, intotwo separate ground-return circuits, according to the well-known McCulloh system. It is found practically nearly impossible to work' ordinaryldirect-current relayson alternating' currents of the frequencies which I propose to use in this sys- 'tem, without employing special adapting and the constantiiull-upor of the customarfiretractile springs; He R ys,

I 'dor not limit my:

' means, as hereinafter described, since such relays,' i f. operated by such currents do not .producefjsufiiciently good contacts etween' :their jarmaturesjjand.ifront V I owing'fto =the' '.-constant alternate magnetiza-- contact: points, tion and demagn'etizatjgn"of" their magnets I cm loy' ini conne'ction wit recti erase and 25 self, to :any particular-.ty e of. rectifier buthave found" a'gthreecell :c ectrolytic "rectifier maticall inJ-F igi-l, tojbeietftactivei and in ';Fig. 2 hag allustratedione of thejjcells 1 of such, a rectifier, Itcomprises-electrodes 34 and'35, electrodes 34 being customarily of-iron :and, electrode or; electrodes 35 being customarily of aluminum. :1 have indicated diagrammatically in Fig. 1, in connection with each of relays 24 and 25, such a threecell 'rectifier having each one aluminum electrode and one iron electrode, while the intcrmcdiae cell has usually two aluminumand one ii jon electrode. For an electrolyte lI have.:lound a solution composed of one i cells,.and the coils of in similar fashion part borax, two arts concentrated ammonia, four parts one acid, and one hundred and twenty eight parts distilled water,- to'beconvenient.

are such,

- .-rectifiers,=that positive pulses pass from one The connection of the cells as is customary with electrolytic side oft-he line through one of the outer through the intermediate cell to the other side :of the line, negative pulses passing from the one side of; the

v,line'lthrough the center cell, the coils of the relay, and the other other side of the line;

outside "cell, .to the it bein a character Y istic of these. electrolytic reet' ers that curj rent can pass through any one cell of the rectifier in one direction only.

.At low frequency (up taco Eper erimposed upon the their armatures indicated diagram:

the relay, and. thence second)- the maintenance of rectifiers such as above descrlbed is not excessive and their performance is fairly constant.

Relays 9, 1 0, 24 and 25 are provided with the hand switches 29 usually provided in relays of the McCul'loh type, and described in the Hamblin patent referred to, foruse in changing from metallic circuit to independent ground-return circuits. The use and effect of such switches being described in said patent, in connection with switches corresponding to switc nos 13 and 28 herein, need not be described here.

Since inductive resistances, such as coils 5 'and' 7, otter only ohmic resistance to direct currents, but offer .very. much greater. resistance to alternating and pulsatory currents, and since condensers, such as 18 and2l, are opaque todirect current, but transparent to alternating currents,-it is practicable, byemploying inductive resistances, 5'and 7 of sufficient retardation, and by employing condensers 18 and 21, to completely isolate, cperatively, the primary 4 I or direct-current circuit 4;, anditsv receiving. set. 6,: from the circuit-.17, andits receiving set,

. alternati n V 20, notwjt standing that both. circuits, and

both receivingsets use the same line conduc-.

tors-'1, 2 ;and groundg '-.'In F ig. .1 the switches 13 and 28-are indicated as'in the position for normal working, that "is to say,- for. working with a complete metallic circuit. =In :this art it is customary to speak of such a system as working norinally when workingon 'a' complete metallic circuit, and to speak ofthewo'rkin as a McCulloh system, or, .as the phrase is; working McCulloh.-, when the system is working with ground return cir cuits. -Alarge non-inductive resistance 30 (say a resistance of about 7000 ohms) is provided in the main circuit in order that the impedance of the line may be composed largely of -resistance,' theresistance of the line itself in a system such as illustrated herein, belng-usuallynot greater than 1000 .ohms. This enables the line relays to keep pace with rapidsignals, and as the values of the line current are small, this resistance does not involve detrimental loss difpower. if this sameresistance .30 were in the line when, by the operation of theswitch 13, the direct current system 'is 'caused to operate as a .McCulloh system, a practical :ditliculty would be presented, since in such case the two ground return circuits of the direct current system, I produced by. reversing 'the switch 13 from the position shown in Fig. 1, would each contain less resistance than the metallic circuit used in normal operation, for. the. metallic circuit contains both relays -9 and 10,eac'h;of large resistance, whereas i the two ground return circuits, when the,

system is operating as a McCulloh system, -'e ach c'ontainsbutone ofthese relays. Thisv change of resistance; when converting the di'-' rect current system into two ground return c1rcu1ts,- 1f not counteracted, would cause I the-working current to'change greatly when changing the system from normal fworkin'g to-lllcCullo-h working, or vice versa, end somight give rise to various troubles i To ob- {late this rhiiicuity I provide special noninductiveresistnnccslil, one for each such ground return circuit, which are of higher value than resistance 30, to compensate for thc exclusion of one of the relaystl nndlO from each ground return circuit, and I pro; vide circuits, and, on switch 13, contacts therefm', whereby resistance-3O 1S 1n the line circuit during normal. working, and one of these resistances 31 is in-one ground return circuit, and the Other'resiStanceBl is iu'the other ground return circult, m'JMcCullohworking. The circuits controlled" by switch l3, h'ywhich resistance 30. is thrown out and res stances 31' thrown in, when changed from normal to McCulloh working, willbe V readily seen vin Fig. .25

1. In practice these resistances 31 are' o about 9600 ohms each;

(it being understood that the values formesistancereferred to throughout this specifi- Cation, .urc approximate, and are subject to:

VtlllittlOll infaceordence with differentoperrent side of the'recciying 'epparutus, asimi-iz or arrangement of. resistances 1S employed,-

iiting conditions) I On the 'alt ernating cur {the normal resistance Bil-being arrnnged to be thrown out of circuit when the switch 28 is shifted fot-McCulloh were-m and othersomewhrt greater resistances; 33 being in eluded, one m each of the ground return,cir-.

cuitsthereby produced.

" In order-to compensate for the decrease in inductance-gin eaclrground return c1rcuit',-gas' compared with the inductance in the math!- lic fci'rcuit, due to the exclusionof one or the other of relays' 9 and lOfrorn ouch ground mum circuit oi the direct current systemwindings 7 only-are incircuit in norma'lor l metallic return workin,, but when switch. 4 ,13 is shi-ftcdf-for McCullol lugs? aretlirown into these :circuitshythe switch 13, each ground return circuit then including on'e winding 7. and one winding This arrangement. obviates the'gi'eaterjeukn'gc' of alternating: current through the direct current side" the inductance coils'7 at the receiving end o i the direct current-system are so arranged that an additional inductive v ilueis added" fo'each .ooil when the system is operating as two ground return circuits. This is'uccom- ,plished hvpro\-'iding theroils 17 with sepa,-

rate windingss'fi'und 1", of which the two 7" connectedin series.

. which would otherwise occur during McCul- 10h working gwithout increasing the in,

ductzmce of tlic direct-current systcin during normal workin As fully citpfiiincd the l'iu ubliu indent .is evidenced at the; cen

1 working, wihd-' referred to, in case the circuit 'should be broken but not grounded, at the'instant of break the armature of relays 9.11mi 10 will (iron and the signal receiving devices-311 and 12 will run continuously instead of intermib tently, as in normal 0 eration. :.';Ihe samewill be true if a break s ould occurin one-of conductor's'l and'2; end in' such-case the attendant will reverse the switch 13, which/-- has the efi'ect-of dividing the circuit of. the

direct: current system into two independent ground l'eturni'circuitsbf which one is served by relay 9. and register 11"and the other is served by relay-410 and' register i I like rsho'uld a break without so ground occur in the alternating circuitl'i',

the armutures of relays 24end =25 will drofi 'l and signal receiiin -deyices'flfi and 27 m operate :contmuous instead 0 f '1l'lte1mli'r tently-as iir-norma operationyand-thereupon the 'attendanflw'iil' reverse' switch- 28.;

which has :the effect-of convertingthe alter-. emit ing current systeminto'ztwo independent ,7 ground. return. circuits. Should the break occur in conductor .1 Lor conductor 2,: r the l I .armatures of all therelaysWIQ,24*aiid25,

will drop, and "the attendant will freverse both switches "13 and 28 Should a" ground occii'r in the circuit 4' "a I v trel sthtiongfli operiation of thewsignalxfreceiving device-'12 .witche's i3 audit? and all of the McCulloh switches 29,;

Inthe-.following claims I use the term rectifierto designate a device which will 'convertcurrent pulses of opposite directions into, e c'urrcnt of one direction'g'thut is' to 'snjg-a direct; current; and I use-=the'term in '1 1-5 .contradistmc-tion' to more asymetric reslstances which merelyexclude-froxn a circuit currents of onedirection whilepermitting 1. A telegraplnsyste n comprising'in c'orn-- biuation'u line conductonia source (xi-supply; of alternating current, aft-ransniitter, a'lme currents; as the other direerelay and n current rectifier be: tween said relay and"-the;line,z-.wlfereby the-- v alternating current of .the dine? isltrnnsforumd. us to saidzreluy, intoai-directcurrent. 5.2- ,A tclcgmph system comprisingin oomhi utt ic ng} inegc nu-l uctor,.n source of; supply l mi - of alternating, current, a transmitter, a line the alternating current system, into a directrelay and an eleetrolytic'rectifier interposed between said relayaiul the line, whereby the alternating current of the line is transformed, as to said relay, into a direct current.

3. A multiplex telegraph system, comprising in combination a direct currentsignaling system and an alternating current signaling system, said two systems comprising a co mnon line conductor, said systems each comprising transmitting and receiving means and a source of current supply, and each comprising means for substantially isolating itself from the other system, the receiving meansot the alternating current system comprising a neutral relay and a, current rectifier interposed between such neutral ire-- lay and the l ne, whereby the alternating current of such alternating current system is converted, as to the said receiving rela of current 4. A multiplex telegraph system ,comprising iii combination a direct current signalingv system and an alternating current signaling system, said two systems comprlsmg a common line conductor, said systems feac-h com-- hand a source of current supply, and each.

comprising means for substantially isolating "itself from the other system, thereceiving ,means of; the alternating current system comprising an electrolytic rectifier interposed between such neutral relay and the line, whereby the alternating: current of its connections to said circu1t,.a ground con-- .neetion, a source of alternating current for said system, two neutral receiving relays, at least one of which is normally connected to;

said circuit, a switch anticonnections therefor arranged at ill-to convert the normal metallic return circuit-including at least one of said relays. into two independent groundv return circuits, each including One-0f said relays. and current-erect-ifying'fmezins inter:

posed between-each such relay and the ne connections thereof, whereby the alternating currentof the line is eonyert -edfasfto each such relay, into atlirect current;

In testimony whereoixl-afllx mysigna-w one, in the presence of two witnesses.

tJosErrr F. D H E; u'imw-m.

H. M. MA new, r

'E. .8. Ross.

sis 

